The present invention relates to diagnostic systems for strobe lamps and their operating circuits and provides a display which enables discrimination between failures of the strobe lamp and of its operating circuit; thus, making maintenance of strobe lamp apparatus efficient, since the entire strobe lamp unit need not be removed for maintenance when the lamp burns and the apparatus can be repaired by replacing the lamp alone.
Strobe lamps are usually installed in locations difficult to reach, such as the roof of a vehicle or on a pole at the top of the vehicle or a machine. When the strobe lamp fails; it is desirable, for efficient maintenance, to know whether only the lamp needs replacement or the entire apparatus needs to be removed for repair.
Heretofore systems for detecting failures have merely indicated the absence of power for driving the strobe lamp. This can be due to the strobe lamp burnout, circuit failure, or loss of power to system. The DC-DC converter of the operating circuit which is used to develop high voltage for the lamp is especially prone to failure. Thus, the maintenance procedures for fixing the strobe unit have required the removal and examination of the entire unit including the operating circuit, the lamp in its socket and the enclosure. It is frustrating and inefficient to remove and replace the lamp (especially when access thereto is difficult) and then to find that the lamp has not failed. Then the entire unit must be removed once diagnosed for failures.
The present invention enables diagnosis without removal of the entire strobe lamp unit. The invention enables maintenance personnel to know whether the lamp failed or the circuit failed and isolates failures to the DC-DC converter. It is a feature of the invention to incorporate the diagnosing facility using circuitry of the strobe lamp unit itself. This failure mode detection facility is provided without redesign of the operating circuit. The principal modification is the addition of an indicator which may be a simple LED (light emitting device) component and programming of the microcontroller which selects the light pulse pattern which the strobe lamp is adapted to emit.
Accordingly, it is the object of the present invention to provide a system for the diagnosis of a strobe lamp unit including the lamp and its operating circuit which discriminates between failures of the lamp and the operating circuit.
Another object of the invention is to provide such a strobe lamp diagnosis facility without redesign of the strobe lamp system and through the use of the circuits within the strobe lamp system itself.
Briefly described, a diagnostic system for a strobe lamp in accordance with the invention utilizes means for detecting when the operating circuit, especially the DC-DC converter thereof, provides voltage to the lamp. Means for example including the microcontroller of the operating circuit which transmits trigger pulses for flashing the lamp is controlled in response to the presence or absence of the operating voltage to the lamp and is programmed so that in the absence of operating voltage the trigger pulses are not produced. Transmission of the pulses from the microcontroller is used to operate a display, which may be implemented by a LED connected in the path of the trigger pulses (for example, in series in the path or in parallel with the path), so that the LED displays (flashes) whether or not the lamp is operational. Failures of the lamp or the operating circuit are isolated since when the trigger pulses are displayed and the lamp does not flash, the burnout of the lamp is indicated; but when the trigger pulses are not displayed and the lamp does not flash failure of the operating circuit is indicated. The diagnostic system is implemented by programming the microcontroller (the device) which generates and transmits the pulses which are used to generate triggers for the strobe lamp, and by the addition of a simple display device, such as the LED.